1. Field of the Invention
This invention relates to new poly-.alpha.-olefin/polyurethane block copolymers (PAO/PU block copolymers), characterized in that they are synthesized from isocyanate-reactive functionalized poly-(C.sub.2 -C.sub.10 -.alpha.-olefins) (hereinafter abbreviated to PAO), preferably polypropylene, di- or polyisocyanates or isocyanate prepolymers and polyols and/or low molecular weight chain extending agents.
The present invention also relates to a process for the production of the PAO/PU block copolymers and to their use as polymer dispersants for the production of polymer blends, as primers or modifiers or for the production of moldings or coatings.
2. Description of the Prior Art
Methods to obtain functionalized PAOs ly in the degradation of high molecular weight non-functional polyolefins in the presence of oxygen, air or ozone, or by grafting with unsaturated carboxylic acids or acid anhydrides, such as maleic acid anhydride for example. Carboxy-modified or carboxylic anhydride-modified PAOs such as these are known per se, but have never been used for the production of PAO/PU block copolymers.
By contrast, PAO/PU blends and mixtures formed solely by physical mixing and not by chemical linkage are known. For example, DE-A 2,720,534 describes PU/polyethylene or PU/polypropylene mixtures for insulating panels.
According to DE-A 2,309,508, polyurethanes having improved flex life are obtained by the addition of from 2 to 30% polyethylene or polypropylene. U.S. Pat. No. 3,670,049 claims inter alia polyethylene and polypropylene as lubricants for PU prepolymers.
U.S. Pat. No. 3,272,890 describes polyethylene or polypropylene molding mixtures containing from 15 to 25% of a thermoplastic polyurethane (TPU).
Polyolefin mixtures with polycondensates or polyurethanes are described in JA 25,175/70 (Toray).
In FR-A 2,163,530, GB-A 1,163,266, GB-A 1,181,727, DE-A 2,740,711/GB-A 1,070,105 and FR-A 1,330,784, polypropylene is modified inter alia by the addition of polyurethanes to improve its dyeability.
Polypropylene-modified PU (prepolymers) are described as hotmelt adhesives in DE-A 2,441,645, JA 56 033,139 and JA 51 114,438.
According to U.S. Pat. No. 3,432,451, polyurethanes are synthesized in the presence of a polyolefin and used as coatings and lacquers.
All of these patents are concerned with physical mixtures of the particular components. There are no covalent bonds between the polyolefins and the polyurethane segments. Accordingly, the basic incompatibility between these chemically very different polymer components cannot be eliminated. This is reflected, for example, in the inadequate mechanical properties of these blends.
According to the present invention, this problem is solved by chemical bond of the polyolefin (PAO) with the PU component. Accordingly, PAO/PU block copolymers such as these may be directly used as moldings or coatings, but more advantageously as primers or compatibility promoters.